Authorities in nutrition and healthcare? recommend that women who plan to become pregnant take supplements of the B vitamin, folic acid or folate, both before becoming pregnant and through early pregnancy to prevent birth defects — especially neural tube defects (NTDs) — in their babies. NTDs include birth defects occurring when the spinal cord and/or brain fail to form normally during pregnancy.?
That there might be a downside to such advice was suggested by studies that found slight increases in the risk of miscarriages in women who took folate along with other vitamin/mineral supplements. A new study reported in the September 8 issue of the British medical journal, The Lancet, however, found no such association between folic acid supplementation and risk of miscarriage.
Jacqueline Gindler, MD, from the Centers for Disease Control and Prevention (CDC) in Atlanta, collaborated with other researchers from the CDC, and with a number of colleagues from Chinese institutions to examine data from the Jiaxing City Collaborative Project on Neural Tube Defect Prevention.
The researchers used data collected by the Chinese Ministry of Health, which in 1993 began a program to prevent NTDs in women who had a premarital examination or were planning to become pregnant for the first time. They were all asked to take a pill containing 400 mcg of folic acid only starting as soon as possible and continuing until the end of the first trimester of pregnancy. Neural tube defects occur during this period because that is when the brain and spinal cord are forming. Compliance with the pill-taking protocol was monitored.
The study lasted two years, and included information on 23,806 women. Of these, 1,871 women did not take any folic acid pills, for a variety of reasons. Compared to the women who did take folic acid, the non-users were slightly older (23.8 vs 23.5 years); had slightly higher education levels; and were less likely to be farm or factory workers.? Otherwise, there were no significant differences in body size or ethnic group.
Dr. Gindler and colleagues found that the overall rate of miscarriage was 9.1 percent.? Importantly, there was no difference in the rate of miscarriage between those women who never took folic acid supplements and those who either took them regularly or who took them at any time. Compared to women who never used the supplements, those who took them regularly had a 3 percent increased risk of miscarriage — a slight difference that was not statistically significant.? In addition, the researchers noted that folic acid supplementation did not affect the stage of pregnancy at which miscarriages occurred, a finding that had been reported in other investigations.
In their discussion, the authors noted that the earlier studies which had found increased rates of miscarriage associated with folic acid supplementation studied women who were using multiple vitamin/mineral supplements. Thus, they suggest that it may have been inaccurate to ascribe such increases to folic acid alone.
In their summary, Dr. Gindlen and coauthors state?” these findings do not support concerns about an increased risk for miscarriages associated with consumption of folic acid during pregnancy.”